Document and Entity Information - shares	3 Months Ended
	Apr. 01, 2017	Apr. 29, 2017
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Apr. 01, 2017
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2017
Entity Registrant Name	KELLOGG CO
Entity Central Index Key	0000055067
Current Fiscal Year End Date	--12-30
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		350,277,682